Chemistry

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Across
  1. 2. smallest part of an element
  2. 5. negative charge
  3. 6. smallest part of an atom
  4. 7. its relative mass number
  5. 9. pure substance
  6. 11. a chemical bond of elements
  7. 12. positive charge
Down
  1. 1. an impure substance
  2. 3. impure substance
  3. 4. neutral charge
  4. 6. number of protons and neutrons
  5. 8. amount of protons
  6. 10. a thing with only one type of atom